[zeromq-dev] ZMQ via load balancer

[Ori Barak]

Hi Guys,

Any ideas regarding the best practices for my scenario or any other ideas on how to distribute events properly between two groups of servers with minimal event loss using ZMQ? This information is very important to us.

Thanks,
Ori

From: Ori Barak
Sent: Tuesday, April 2, 2013 7:24 PM
To: 'zeromq-dev at lists.zeromq.org'
Subject: ZMQ via load balancer

Hello All,

I hope this is the right distribution list for these type of questions.

I have couple of question regarding the best practices of using ZMQ with load balancer.

First Q:
In my scenario I use push\pull sockets where the push socket's endpoint is a virtual IP (VIP) returning one of the physical machine's IP behind the VIP implemented by software load balancer. I use this reconnection pattern since my service lives in an environment where the SLA is that 10% of the servers might be down in any given time so to support the SLA I'm refreshing the connection every once in a while and I reconnect to the VIP endpoint every couple of seconds.
Is there a better approach to work with ZMQ given my constraints?

Second Q:
Regarding send\receive high watermark. I noticed that data that cannot be sent right away is saved in memory per TCP 4 tuple, (client_ip, client_port, destination_ip, dest_port) so if I'm using the reconnection technique I mentioned before than the new connection will not get the data in memory from the previous connection. So in a scenario where:

*         Server A is pushing data to server B.

*         B is dead

*         After ~10 sec A is reconnecting via the virtual IP and get server C
For the 10 seconds between reconnection the data could not be pushed to B and was saved in sender memory. After reconnecting the data will not get to C since the new connection will get different client port.

So... Is there a way to get these events after reconnecting?

Thank you very much,
Ori



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